A friend of mine forwarded me a conversation that one of her friends was having on her Facebook wall. I include some of her points below:

SPEAKER A: Global warming is a natural phenomenon, much like summer versus winter. There have been warming periods historically (the late Dark Ages, Early Middle Ages during the Viking Expansion), and there have been cooling periods (such as the 17th …Century). Man did not cause them and is not causing it now. We can’t fix it. It will fix itself. We don’t have to embrace socialism to escape what is in reality a natural cycle. The sky isn’t falling.

SPEAKER B: The global warming proponents (the smart ones at least) don’t deny the cyclical nature of the earth’s temperature – however, they believe that human factors have sped up the warming cycle. Just like the liberals think that the “denialists” are denying that the earth is warming at all. The only intelligent debate is the extent of the human impact (if any) on these natural cycles.

SPEAKER A: The problem I have with them is that it seems that socialism and other coercive plans are the only fixes that they will entertain. I’m not against common sense things, such as cleaning up the environment and trying to find cleaner fuels/technology. But a lot of them use hysteria and outright lying to advance their agenda. That’s despicable.

SPEAKER B: True. My only point is that in the heat of the debate, both sides appear to misrepresent what the other is arguing.

Let’s first clear up the science. Evidence indicates that Earth experiences an Ice Age every 100,000 years or so, a cycle I will refer to as “slow climate change.” Scientists have also discovered that a higher amount of carbon dioxide in the atmosphere (usually measured in parts-per-million, or ppm) is very tightly correlated with a higher average planetary temperature. During the Ice Ages, the atmospheric concentration of CO2 on our frigid planet was approximately 180ppm. Immediately preceding the Industrial Revolution, when temperatures were 8°C warmer, CO2 levels were closer to 280ppm.

The factors responsible for slow climate change are complicated and involve continental drift, the amount of land mass near the poles (which changes as a result of plate tectonics), a form of heat transfer between the poles and the equator known as the thermohaline, the amount of global snowcover, and the overall albedo (or reflective-ness) of the Earth.

So reflect on this for a moment: the difference in CO2 concentrations between Ice Ages (180ppm) and preindustrial times (280ppm) is 100ppm. To visualize, imagine splitting the air into 10,000 separate packets containing all the gases of the atmosphere like nitrogen, oxygen, and so on. In the mid-1800’s 3 of those 10,000 packets were carbon dioxide. During the Ice Ages, 2 were. In other words, a change in CO2 concentration as small as 1 part in 10,000 is the difference between Earth as we know it and an Ice Age.

Today, as a result of human activity, the amount of CO2 in our atmosphere is 390ppm (about 4 packets), higher than it’s been for at least one million years. So if 2 packets equals an Ice Age and 3 packets equals modern times, what happens now that Earth is passing 4 packets and approaching 5? As I detail below, all of Earth’s systems change and in most cases, for the worst.

The other crucial point is that Earth’s transition from 280ppm to 390ppm has occurred in only about 150 years. So while slow climate change happens over hundreds of millennia, this new “fast climate change” is occurring in a just a few generations. This is not nearly enough time for ecosystems to adapt and is one of the reasons the Earth is in the midst of the largest extinction since that which killed off the dinosaurs. This is substantially different than the “natural” climate change to which people often refer.

That climate can change both slowly due to natural processes and quickly due to human activity should not come as a surprise. Anything that causes the planet to gain or lose significant amounts of heat can lead to a changing climate. The science is quite simple. Organic matter like oil, coal, and trees contain carbon. When those are burned or left to decay that CO2 is released into the atmosphere. As simple experiments can show, carbon dioxide traps heat. As more CO2 accumulates in the air, the planet warms. The fundamental science is really just that simple. To argue that climate varies slowly and “naturally” over long time scales is correct, but to argue that it ONLY varies “naturally” over long time scales is not.

The other argument I often hear is that the Earth’s climate will simply fix itself; it always has and it always will. However, this is merely an assertion with no scientific backing behind it. What the argument ignores is that 1) historically this healing process has typically required thousands of years and 2) given the extremely fast rate at which our climate is changing, there is no guarantee the old models still apply.

The real problem is that unlike some things like sulfates which remain airborne for only a couple years, CO2 remains in the atmosphere for hundreds to thousands of years. Scientists have been carefully tracking carbon dioxide levels since the 1950’s and have found that the concentration has increased more rapidly during the last 60 years than during any other time period in the geological record.

The objection that I have to these comments atop the page is that the word “liberals” is brought into it. These scientific results have absolutely nothing to do with politics. Anyone who introduces it into a climate discussion is viewing the science with an eye towards political ideology, and that is dangerous on both sides. There are many reasons why people deny that climate change is happening. Some dislike the solutions, which involve mitigation of emissions or other actions interpreted as part of a “socialist takeover.” Others view the problem as so intractable that denial is the only sane option. But again, the range of proposed solutions should have absolutely nothing to do the veracity of the science.

Even if you are not convinced that humans are primarily responsible for driving current global climate change, a lot of really smart people who’ve spent much of their lives studying this issue are. If they are wrong and we take significant (but ultimately unnecessary) corrective actions, the worst-case scenario is that mitigation wastes money, damages the economy, and causes job losses. But if the scientists are right and we do nothing, the worst-case scenario is that we irreversibly ruin the planet’s ability to provide sustainable habits, water, food, and ecosystems for at least thousands of years. One set of outcomes is bad, but the other is catastrophic.

To use an analogy, consider the purchase of fire insurance for one’s home. Although the probability of fire is low, if one did occur, failure to have taken appropriate precautionary measures would have been a devastating mistake. This is the essence of risk, which is measured as the product of the probability of an event with the cost of that event. A situation becomes increasingly risky as a negative outcome grows more likely or as the cost of that outcome rises. Given that the probability of negative climate outcomes is exceptionally high (possibly at 100%) and the potential costs are incalculable, inaction on climate change is, without exaggeration, the riskiest behavior humanity has ever taken. For honestly open-minded people who accept that maybe, just maybe, the other side is right, the conclusion is inescapable: we must act to mitigate global climate change and we must do so now.

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About Me

Hi, I’m Mike Specian. I am currently a AAAS Science & Technology Policy Fellow hosted at the U.S. Department of Energy. This site is a repository for things that matter to me including science, energy, climate, public policy, and photography from around the world. You can follow me on Twitter, through an RSS feed or by subscribing to email updates below.